1. Field of the Invention
The present invention relates generally to a display device, and more specifically, to a display device capable of reducing bubbles in sealants.
2. Description of the Prior Art
Reading words or pictures printed on paper is the most accepted reading method for human beings. As paper printing techniques have advanced and printing costs have lowered, paper has been extensively used as a data storage medium. However, as display techniques advance, it is possible that in the near future, paper may be replaced by various types of display device, particularly an electrophoretic display (EPD). Like paper, the electrophoretic display is thin in profile, small in size, lightweight, easy to carry, and flexible. Therefore, it is expected that the electrophoretic display can be applied in electronic paper or electronic books, replacing conventional paper and books.
Refer to FIG. 1 and FIG. 2. FIG. 1 and FIG. 2 schematically depict a conventional electrophoretic display device, wherein FIG. 1 is a cross-sectional view taken along line A-A′ of FIG. 2. The conventional electrophoretic display device 100 comprises a backplane 102, a frontplane 104, and an electronic ink material layer 106 located between the backplane 102 and the frontplane 104. Since the optical properties of the electronic ink material layer 106 are prone to be affected by water vapor, the electrophoretic display device 100 usually further comprises a barrier layer 108 formed on the frontplane 104, and a sealant 110 formed on the periphery of the frontplane 104, the backplane 102 and the barrier layer 108 in a packaging process to avoid wafer vapor from invading the electronic ink material layer 106. For purposes of clear illustration of each element, the sealant 110 is not shown in FIG. 2.
As shown in FIG. 1 and FIG. 2, in order to transfer the common voltage (Vcom) from the backplane 102 to the common electrode (not shown) of the frontplane 104, the electrophoretic display device 100 in the prior art also has a silver gel disposed on a frontplane ear 112 protruding from the frontplane 104, and the barrier layer 108 may usually have a corresponding barrier layer ear 113. However, due to poor design of the frontplane ear 112 and the barrier layer ear 113, bubbles tend to appear in the sealant 110 formed in the packaging process, which will result in defects. Refer to FIG. 3, which is a partial enlarged diagram of an area B in FIG. 2. As shown in FIG. 3, due to the right-angle design of the frontplane ear 112 and the barrier layer ear 113, the distance between a turning point of the frontplane ear 112 and the barrier layer ear 113 may be different or too large compared with the distance between other positions of the frontplane ear 112 and the barrier layer ear 113. For example, the distance d1 between the corners of the turning points is larger than the distance d2 between the two parallel surfaces. Under these conditions, the sealant 110 can only spread inward from the edge of the barrier layer 108 through the distance d2, but can not reach the distance d1. Thus, the sealant 110 cannot fill the turning point. As a result, bubbles 116 will be formed at the turning point after curing the sealant 110. The bubbles 116 not only reduce water-proofing capability of products, giving rise to lower reliability of products, but also form holes in the sealant 110, which tend to burst during thermal curing.